The current invention concerns a system for ventilating an enclosure housing equipment which forms a part of the emergency feedwater system in a nuclear power plant. More specifically, the invention concerns a system for ventilating an enclosure, housing a steam turbine and an emergency feedwater pump driven by the steam turbine, using an eductor powered by steam exhausted from the steam turbine.
Nuclear power plants frequently employ an emergency feedwater system to provide a back-up source of feedwater to the steam generator in the event that an accident or upset in the primary feedwater system causes the water level in the steam generator to drop below the minimum desired level. Such an emergency feedwater system may include an emergency feedwater storage tank, containing sufficient water for approximately one day of operation of the steam generator, a motor driven pump, and a steam turbine driven emergency feedwater pump for transferring water from the tank to the feedwater inlet to the steam generator. The steam turbine driven pump serves to deliver feedwater to the steam generator in the event of a loss of electrical power.
In order to protect the emergency feedwater pump and its driver steam turbine from harm due to hurricanes, tornadoes, projectiles, etc., this equipment is enclosed in a concrete pump room. The pump room itself may be enclosed within a large auxiliary building adjacent to the containment. The life of the pump is severely reduced by exposure to excessive environmental temperatures. Unfortunately, the steam turbine and its associated piping, and the pump itself, transfer heat into the pump room. Hence, it is important to ventilate the pump room to ensure the excessive build-up of heat is avoided. An electrically operated fan can be used to draw ventilating air through the pump room. However, it is vital that the turbine driven emergency feedwater pump be operable during electric power failures.
Probabilistic risk analysis has shown that loss of all AC electrical power poses one of the highest risks to the safety of the public. Accordingly, it would be desirable to provide a ventilating system for the pump room which was not dependent on electrical power.